Integrated hydrocarbon conversion process

ABSTRACT

An integrated hydrocarbon conversion process for converting a heavy hydrocarbon feedstock boiling above 650*F. into various valuable products including gasoline, jet fuel, and coke, which comprises: A. HYDRODESULFURIZING THE FEEDSTOCK IN A HYDRODESULFURIZATION ZONE; B. CATALYTICALLY CRACKING AT LEAST A PORTION OF THE FRACTION FROM THE HYDRODESULFURIZATION ZONE BOILING IN THE RANGE OF ABOUT 650* TO ABOUT 1000*F.; c. feeding at least a portion of the decant oil from the catalytic cracking zone and at least a portion of the fraction from the hydrodesulfurization zone boiling above about 1,000*F. to a coking zone and coking the mixture; D. RECYCLING AT LEAST A PORTION OF THE CATALYTIC CRACKER CYCLE OIL AND THE COKER GAS OIL TO THE HYDRODESULFURIZATION ZONE; AND E. RECOVERING AS PRODUCTS OF THE INTEGRATED HYDROCARBON CONVERSION PROCESS AT LEAST GASOLINE, JET FUEL, AND COKE.

United States Patent 1 1 Walkey INTEGRATED HYDROCARBON CONVERSIONPROCESS [75] Inventor: John E. Walkey, Richmond, Calif. [73] Assignee:Chevron Research Company, San Francisco, Calif.

[22] Filed: June 21, 1973 [21] App]. No.: 372,117

[52] US. Cl. 208/50; 208/58; 208/89; 208/93 [51] Int. Cl Cl0g 37/06 [58]Field of Search 208/58, 89, 93, 50

[56] References Cited UNITED STATES PATENTS 2,871,182 1/1959 Weekman208/50 3,493,489 2/1970 Naniche 208/50 3, 17,501 11/1971 Eng et a1208/97 3,684,688 8/[972 Roselius 208/50 3,704,224 1 1/1972 Scovill eta1. 208/50 3,775,290 11/1973 Peterson ct 211...... 208/89 PrimaryE.raminerHerbert Levine Attorney. Agent, or Firm-G. F. Magdeburger; R.H. Davies 1111 3,891,538 [451 June 24, 1975 5 7] ABSTRACT An integratedhydrocarbon conversion process for converting a heavy hydrocarbonfeedstock boiling above 650F. into various valuable products includinggasoline, jet fuel, and coke, which comprises:

a. hydrodesulfurizing the feedstock hydrodesulfurization zo'ne;

b. catalytically cracking at least a portion of the fraction from thehydrodesulfurization zone boiling in the range of about 650 to about1000F.;

c. feeding at least a portion of the decant oil from the catalyticcracking zone and at least a portion of the fraction from thehydrodesulfurization zone boiling above about 1,0000? to a coking zoneand coking the mixture;

d. recycling at least a portion of the catalytic cracker cycle oil andthe coker gas oil to the hydrodesulfurization zone and e. recovering asproducts of the integrated hydrocarbon conversion'process at leastgasoline, jet fuel, and coke.

ina

2 Claims, 1 Drawing Figure a a o E CATALYTIC z CRACKING o GASOLINE ZONE1: ATMOSPHERIC u RESIDUUM 6 M g CYCLE OIL 2 GASOLINE DECANT 011.

w (I I 4 o JET HYDRO- l;

aDESULFUR' z DlESEL p IZATION g 15 ZONE U c4 u a 650 1000 F. g a: l2 l40 .3 :2

0 HYDROGEN s comnc z GASOLINE zone 12 g E ,7 COKER GAS OIL COKE 1INTEGRATED HYDROCARBON CONVERSION PROCESS BACKGROUND OF THE INVENTION Acontinuously rising demand for crude oil combined with a shrinkingsupply has created what is now being referred to in the United States asan energy crisis. In view of these conflicting developments, it isincumbent upon refiners to squeeze every last possible drop of usefulproduct out of each barrel of crude oil. The combination of processesfor the refining of heavy hydrocarbon feedstocks boiling above 650F.which will optimize the yields and selectivity of the products obtainedis particularly desirable since these feedstocks, e.g., atmosphericresiduum, are generally of low value and difficult to process.

The subject invention is directed to the combination of three processesin a unique manner which concurrently improves (1) product yields andproduct qualities from the combined processes while (2) improving theefficiency of all three processes.

SUMMARY OF THE INVENTION An integrated hydrocarbon conversion processfor converting a heavy hydrocarbon feedstock boiling above 650F. intovarious valuable products including gasoline, jet fuel, and coke, whichcomprises:

a. hydrodesulfurizing the feedstock in a hydrodesulfurization zonethereby obtaining an effluent comprising gasoline, jet fuel, a fractioncomprising material boiling in the range of from about 650 to about1000F., and a fraction comprising material boiling above about l000F.;

b. catalytically cracking at least a portion of the fraction from thehydrodesulfurization zone boiling in the range of about 650 to about1000F., thereby obtaining an effluent comprising gasoline, catalyticcracker cycle oil, and a decant oil;

c. feeding at least a portion of the decant oil and at least a portionofthe fraction from the hydrodesulfurization zone boiling above about1000F. to a coking zone and coking the decant oil and the fractionboiling above about I000F., thereby obtaining an effluent comprisinggasoline, coker gas oil and coke;

d. recycling at least a portion of the catalytic cracker cycle oil andthe coker gas oil to the hydrodesulfurization zone and hydroconvertingthe catalytic cracker cycle oil and coker gas oil therein; and

e. recovering as products of the integrated hydrocarbon conversionprocess at least gasoline, jet fuel, and coke.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic flow diagramof one embodiment of the process.

DETAILED DESCRIPTION OF THE INVENTION The subject invention is directedto an integrated hydrocarbon conversion process for converting heavyhydrocarbon feedstocks boiling above 650F. and containing substantialquantities of materials boiling above l000F. into various valuableproducts in good yield and with good selectivity for producing the morevaluable products. The process of the subject invention utilizes ahydrodesulfurization zone, a catalytic cracking zone, and a coker, in aparticular mode of operation which optimizes the operating efficiency ofall three units.

The method of operation has been summarized above under SUMMARY OF THEINVENTION." It will be described in more detail hereinafter. Basicallyit calls for an integrated process combining hydrodesulfurization,catalytic cracking and coking. Products recovered using the integratedprocess of this invention include at least gasoline, jet fuel and coke.

Additionally, diesel fuel may be recovered as well as middle distillatesfor use as fuel oil. Light gases are also produced which may be handledby conventional means and used for conventional purposes.

HEAVY HYDROCARBON FEEDSTOCKS The heavy hydrocarbon feedstocks utilizedin the subject invention comprise hydrocarbons boiling above about 650F.and contain substantial quantities of material boiling above I000"F. Atypical feedstock is that normally produced as the residuum product fromatmospheric-pressure distillation of crude oil. The initial boilingpoint of the feedstock can be as low as about 350F. if it is desired tohydrodesulfurize the 350 to 650F. boiling range fraction in the crudeoil. Other feedstocks include heavy hydrocarbons recovered from tarsands, synthetic crude oil recovered from oil shales, heavy oilsproduced from liquefaction of coal, etc. The hydrocarbon feedstocks willgenerally contain at least about 10 percent of materials boiling aboveI000F.

OPERATING CONDITIONS IN THE HYDRODESULFURIZATION ZONEHydrodesulfurization of the heavy hydrocarbon feedstock is carried outat conventional operating conditions which will generally include atemperature in the range of about 650 to about 850F., preferably withinthe range of from about 700 to about 800F., a liquid hourly spacevelocity of from about 0.1 to about 3, preferably about 0.3 to about L5,and a pressure of from about 500 to about 3,000 psig, preferably about1,000 to about 2,000 psig.

The hydrogen supply rate (makeup and recycle hydrogen) to thehydrodesulfurization zone will generally be in the range of from about500 to 20,000 SCF/barrel, preferably in the range from about 1,000 toabout 10,000 SCF/barrel of feed, and more preferably in the range offrom about 2,000 to about 4,000 SCF/barrel.

While hydrodesulfurization of the hydrocarbon feedstock fed to thehydrodesulfurization zone is the primary purpose of this zone, otherreactions encompassed within the term hydroconversion, e.g.,hydrogenation and hydrodenitrification, may be occurring.

HYDRODESULFURIZATION CATALYST The hydrodesulfurization catalyst utilizedin the subject invention can comprise any conventionalhydrodesulfurization catalyst. Normally these catalysts comprisecomposites comprising at least one hydrogenating component selected fromGroup VI metals and compounds of Group V] metals and at least onehydrogenating component selected from Group VIII metals and compounds ofGroup VIII metals together with a refractory support such as alumina,silica-alumina, silicaalumina-titania, and combinations of amorphousinorganic oxides with a zeolite.

A preferred hydrodesulfurization catalyst comprises a carrier of aluminain which discrete, substantially insoluble metal phosphate particles aredispersed in said carrier and consisting essentially of at least onemetal phosphate selected from phosphates of the zirconium, titanium,tin, thorium, cerium and hafnium, and containing substantially theentire phosphorus content of the said catalyst. Preferred insolublemetal phosphate components are phosphates of zirconium and titanium.

The general type of insoluble metal phosphate containing catalyst andprocedure for making this catalyst is disclosed in U.S. Pat. Nos.3,546,105 and 3,493,517, both of which patents are incorporated hereinby reference. As in U.S. Pat. No. 3,546,]05, substantially no silica orpotentially deleterious fluorine are present in these preferredcatalysts.

OPERATING CONDITIONS IN THE CATALYTIC CRACKING ZONE Operating conditionsutilized in the catalytic cracking zone of the subject invention arethose conventional in catalytic cracking of hydrocarbon feedstocks.These generally include a temperature in the range of from about 850 toabout llF., a pressure in the range of from about 1 to about 100 psig,preferably to 30 psig. The liquid hourly space velocities within thecatalytic cracking zone will generally fall within the range of fromabout 1.5 to about 50, although space velocities as high as I00 or morein riser cracking units may be used. Preferred temperatures for use inthe catalytic cracking zone will generally fall within the range of fromabout 850 to about I050F.

The catalytic cracking process step including regeneration of thecatalyst may be performed utilizing wellknown techniques, including, forexample, fluidized bed or moving bed processes.

CATALYTIC CRACKING CATALYSTS The catalysts used in the catalyticcracking zone in the process of the present invention are thoseconventionally utilized in catalytic cracking processes. For example,activated, naturally occurring catalytic cracking catalysts such asclay, i.e., kaolin, can be used, as well as synthetic clays such asthose disclosed in U.S. Pat. No. 3,252,889, and semi-synthetic catalystssuch as silica-alumina to which kaolin has been added. Syntheticallyprepared cracking catalysts containing amorphous silica-alumina, with orwithout additional promoters, can also be used. ZeoIite-containingcatalysts may also be used to reduce coke formation. Methods ofpreparation of the amorphous catalytic cracking catalysts are wellknown. The crystalline zeolitic aluminosilicate catalysts are disclosedand discussed in great detail in U.S. Pat. Nos. 3,2l0,267 and 3,27I,4l8.As is disclosed in these two prior art patents, the crystalline zeoliticmolecular sieve component may have included therewith an amorphousmatrix, for example, silicaalumina, titania, zirconia, magnesia, and thelike.

It should be recognized that different hydrocarbon feeds presentdifferent problems and the catalyst used will, in general, be tailoredto fit the particular needs of the hydrocarbon feedstock being used.

OPERATING CONDITIONS IN THE COKING ZONE The coking zone in the subjectinvention utilizes conventional operating techniques and conditions.Typically, it may comprise either one of two different types of cokingsteps; namely, delayed coking or fluid coking. These are described indetail in U.S. Pat. No. 3,493,489, the disclosure of which is herebyincorporated by reference. Additional patents including U.S. Pat Nos.3,537,975 and 3,5l8,l82 discuss fluid coking and delayed coking,respectively.

DEFINITIONS OF TERMS The term decant oil," as used herein, means theheavy bottoms fraction of the effluent from the catalytic cracking zone.Typically it will boil in the range 800 to about I000F.

The catalytic cracking cycle oil which is recycled (at least in part) tothe hydrodesulfurization may encompass both the light cycle oiltypically boiling in the range 430 to 650F., and the heavy cycle oiltypically boiling in the range 650 to 800F. Part of this catalyticcracker cycle oil may also be recovered for use as fuel oil.

The coker gas oil" referred to herein typically boils in the range of400 to 900F.

The term Cf means hydrocarbons having 4 or less carbon atoms. Cfhydrocarbons recovered in fractionator 5 will be saturated. Off offractionator 9, the C, hydrocarbon fraction will contain unsaturatedhydrocarbons. Similarly, the C hydrocarbon fraction from fractionator I5may also contain unsaturated compounds.

PROCESS OPERATION Referring now to the drawing which represents apreferred embodiment of the present invention, an atmospheric residuumboiling above 650F. is fed by line 1 to hydrodesulfurization zone 2.Hydrogen is introduced into hydrodesulfurization zone 2 via line 3. Theeffluent from hydrodesulfurization zone 2 is fed by line 4 tofractionator 5 where various cuts are taken off as noted in the drawing.This fractionator may consist of two stages, i.e., an atmospheric columnand a vacuum column. A fraction comprising hydrocarbons boiling in therange of from 650 to l000F. is fed by line 6 to eatalytic cracking zone7. The effluent from catalytic cracking zone 7 is fed by line 8 tofractionator 9 wherein various cuts are obtained, as indicated in thedrawing. A catalytic cracking cycle oil which comprises material boilingin the range of 430 to 800F. is removed by line 10 and recycled tohydrodesulfurization zone 2. A decant oil comprising material boilingabove about 800F. and primarily in the range of 800 to I000F. is removedby line I1 and sent by lines ll and 12 to coking zone 13. Additionalfeed to coking zone 13 comprises the material boiling above I000F. fromhydrodesulfurization zone 2. This material is fed to coking zone I3 byline 12. The effluent from coking zone 13 is sent by line 14 to afractionator 15 wherein various cuts are removed as noted in thedrawing. A coker gas oil is recycled by line 16 to hydrodesulfurizationzone 2. Coke is removed by line 17.

By the process described in the figure, liquid products, includinggasoline, jet fuel, diesel fuel as desired, and coke are obtained ingood yield and with high selectivity for the most desirable products,e.g., gasoline and jet fuel.

As is evident from the drawing, the feed to the catalytic cracking zoneis desulfurized and hydrogenated in hydrodesulfurization zone 2. Ratherthan recycling the catalytic cracking zone cycle oil to the catalyticcracking zone as is conventionally done. the catalytic cracking cycleoil is recycled to the hydrodcsulfurization zone to improve its qualityas a product and as feedstock to the catalytic cracking zone.

Rather than feeding coker gas oil to the catalytic cracking zone as isconventionally done. it is recycled to the hydrodesulfurization zone forhydrogenation to improve its quality as a catalytic cracking zone feed.Middle distillate boiling range products derived from catalytic crackingand coking are then hydrogenated in the hydrodesulfurization zone andcan be drawn off as product from fractionator 5 as desired.

The benefits derived from this process and combination are derived inpart from the introduction of distillate stocks. i.e., a catalyticcracking zone cycle oil and coker gas oil. into the hydrodesulfurizationzone together with the hydrocarbon feedstock. From the standpoint ofoperating efficiency, this is more effective than utilizing separatehydrodesulfurization zones for these materials. Additionally, improveddesulfurization can be obtained by combining lower boiling components.i.e.. cycle oil from the catalytic cracking zone and coker gas oil withthe heavy hydrocarbon feedstock to a desulfurization zone. Further.hydrodesulfurization of the coker feed improves the yields and thequality of products from the coking zone. Similarly, the hydrogenationof coker gas oil before feeding it to a catalytic cracking zone improvesits quality as catalytic cracking zone feed. Similarly, hydrogenation ofthe 650 to I000F. boiling range stock in the heavy hydrocarbon feedimproves its quality as catalytic cracking zone feed.

ln summary, the unique integrated combination of processing steps of thesubject invention provide improved feedstocks to each of the threeprocessing zones. Improved operating efficiency results together withimproved yields of high quality products.

it is apparent that many widely differing embodiments ofthis inventionmay be made without departing from the scope and spirit thereof; and.therefore, it is not intended to be limited except as indicated in theap pended claims.

What is claimed is:

1. in a process wherein an atmospheric residuum hydrocarbon stockcontaining sulfur and substantial quantities of materials boiling above1000F. is hydrotreated in a hydrotreating zone. a low sulfur gasolineproduct and a low sulfur jet fuel product are recovered from theeffluent from said hydrotreating zone. a low sulfur portion of saideffluent is catalytically cracked in a catalytic cracking zone; at leasta portion of said effluent boiling above 1000F. is coked in a cokingzone. a gasoline product is recovered from the effluent from saidcatalytic cracking zone. a portion of the effluent from said catalyticcracking zone is recycled to said hydrotreating zone. and a gasolineproduct is recovered from the effluent from said coking zone. theimproved method of optimizing the operating efficiency of thecombination of said hydrotreating. catalytic cracking and coking zoneswhich comprises:

l limiting to 800F. the end point of said portion of said effluent fromsaid catalytic cracking zone that is recycled to said hydrotreatingzone;

2 passing to said coking zone and coking the portion of said effluentfrom said catalytic cracking zone that boils above 800F.;

3 recovering coke from said coking zone in increased yield compared withthe yield if the portion of said effluent from said catalytic crackingzone boiling above 800F. were not coked in said coking zone;

4 recycling from said coking zone to said hydrotreating zone a coker gasoil in increased amount compared with the amount available for suchrecycle if the portion of said effluent from said catalytic crackingzone boiling above 800F. were not coked in said coking zone;

whereby there is obtained increased coke yield. increased coker gas oilfor recycle to said hydrotreating zone, and improved desulfurizationefficiency in said hydrotreating zone, with a resulting increasedefficiency of operation of the combination of said hydrotreating,catalytic cracking and coking zones.

2. A process as in claim 1 wherein the catalyst in said hydrotreatingzone comprises a Group Vl-B component, a Group VIII component, arefractory component and insoluble metal phosphate particles dispersedthrough said refractory component.

1. IN A PROCESS WHEREIN AN ATMOSPHERIC RESIDUUM HYDROCARBON STOCKCONTAINING SULFUR AND SUBSTANTIAL QUANTITIES OF MATERIALS BOILING ABOVE1000*F IS HYDROGENATED IN A HYDROGENATING ZONE, A LOW SULFUR GASOLINEPRODUCT AND A LOW SULFUR JET FUEL PRODUCT ARE RECOVERED FROM THEEFFLUENT IS CALYTICALLY ING ZONE, A LOW SULFUR PORTION OF SAID EFFLUENTIS CATALYTICALLY CRACKED IN A CATALYTIC CRACKING ZONE; AT LEAST APORTION EFFLUENT BOILING ABOVE 1000*F IS COKED IN A COKING ZONE, AGASOLINE PRODUCT IS RECOVERED FROM THE EFLUENT FROM SAID CATALYTICCRACKING ZONE, A PORTION OF THE EFFLUENT FROM SAID CATALYTIC CRACKINGZONE,IS RECYCLED TO SAID HYDROTREATING ZONE, AND A GASOLINE PRODUCT ISRECOVERED FROM THE EFFLUENT FROM SAID COKING ZONE, THE IMPROVED METHODOF OPTIMIZING THE OPERATING EFFICIENCY OF THE COMBINATION OF SAIDHYDROTREATING, CATLAYTIC CRACKIING AND COKING ZONES WHICH COMPRISES: 1.LIMITING TO 800*F, THE END POINT OF SAID PORTION OF SAID EFFLUENT FROMSAID CATALYTIC CRACKING ZONE THAT IS RECYCLED TO SAID HYDROTREATINGZONE; 2 PASSING TO SAID COKING ZONE AND COKING THE PORTION OF SAIDEFFLUENT FROM SAID CATALYTIC CRACKING ZONE THAT BOILS ABOVE 800*F;
 2. Aprocess as in claim 1 wherein the catalyst in said hydrotreating zonecomprises a Group VI-B component, a Group VIII component, a refractorycomponent and insoluble metal phosphate particles dispersed through saidrefractory component.
 3. RECOVERING COKE FROM SAID COKING ZONE ININCREASED YIELD COMPARED WITH THE YIELD IF THE PORTION OF SAID EFFLUENTFROM SAID CATALYTIC CRACKING ZONE BOILING ABOVE 800*F WERE NOT COKED INSAID COKING ZONE;